[Intraoperative flow measurement of coronary bypass grafts using the ultrasound transit time flowmeter]

The aim of the study was to compare the mean and maximum flow and the flow pattern of coronary vein grafts (SVG) supplying target vessels of the inferior and lateral wall with internal mammary (IMA) grafts to the left anterior descending artery (LAD). In 21 patients 25 bypass grafts (13/25 SVG, 12/25 IMA) were investigated. Using the transit time ultrasound method, flow was measured every 5 ms and the flow data of 60 s were acquired. The flow pattern showed significant differences between both graft types during their cycle. IMA grafts showed only one peak occurring after 22.1+/-12.3% and the second after 63.4+/-15.5% of their cycle. The mean flow was not different in both graft types (IMA: 45.3+/-27.0 ml/min and SVG: 41.8+/-26.7 ml/min, p = n. s.) as it was the case for the maximum flow (IMS: 98. 4+/-45.2 ml/min and SVG: 75.7+/-55.4 ml/min, p = n. s.). In conclusion, there is a different flow pattern for both graft types concerning the number and the occurrence of flow-peaks in the bypass cycle. The mean and peak flow showed no significant difference.